This disclosure relates to an acid fuel cell, such as a phosphoric acid electrolyte fuel cell. More particularly, the disclosure relates to a condenser heat exchanger for use in an acid fuel cell.
One type of acid fuel cell uses a phosphoric acid electrolyte. Typically, a condenser is used in conjunction with the phosphoric acid fuel cell to condense and remove water from a gas stream, such as anode or cathode exhaust. One type of condenser heat exchanger uses multiple tubes supported in multiple fins. A coolant flows through the tubes to condense water from the gas stream flowing between the fins. The water vapor in the gas stream includes a small amount of phosphoric acid. The heat transfer fins at an upstream portion of the condenser heat exchanger have exhibited corrosion due to acid condensation on the fins. The fin edge temperature is much higher than the coolant temperature due to the heat resistance through the fin. As a result, the fin edge temperature is typically higher than the water dew point but lower than the acid dew point, which causes strong acid condensation on the fin leading to corrosion build-up.
Corrosion products must be removed during a maintenance procedure to prevent condenser corrosion and the fins from becoming blocked, which could inhibit the gas stream flow through the condenser heat exchanger. Corrosion-resistant metals, such as stainless steel and HASTELLOY, have been used for the fins and tubes. Use of corrosion-resistant metals has not extended the maintenance interval for removing corrosion products from the condenser heat exchanger to a desired duration, which may be ten years or more.